Powder spraying systems are well known. A typical powder spraying system includes a powder source, such as powder stored in a fluidizing hopper. The powder in the hopper may be fluidized using pressurized air, although not all powder spray systems use fluidized powder supplies. The spraying system also includes a powder spray device such as a spray gun that extends into a spray booth. The spray gun is used to spray powder at an object inside the booth. The spray booth is used for powder containment and recovery. Many types of spray guns have been developed over the years including electrostatic guns such as corona spray guns and tribo-charging guns. Most powder spraying systems also include a powder collection system to collect powder overspray. Some powder spraying systems use non-electrostatic spray guns.
In many powder spray systems, it is desirable to be able to move a spray gun or a plurality of spray guns automatically toward and away from the object being sprayed. For example, a gun mover that is positioned outside the spray booth may be used to position spray guns into and retract spray guns from a spray booth through suitable openings in the spray booth wall structure. Known gun movers, including gun movers such as are described in U.S. Pat. No. 4,616,782 and in co-pending U.S. patent application Ser. No. 09/589,946 for PNEUMATICALLY CONTROLLED SPRAY GUN MOVER, both of which disclosures are fully incorporated herein by reference, include the capability of horizontal positioning as well as vertical positioning of one or more guns mounted on, the gun mover. Vertical movement of the guns during a spraying operation is also commonly effected by an oscillator device.
Spray guns are typically mounted on known gun movers via a series of vertical and horizontal gun mount bars or tubes. The spray gun bodies are secured to the horizontal bars by bracket assemblies that can be slipped onto the bars and tightened. One drawback of such known gun mounts is that the initial mounting position of the gun is not easily or reliably repeatable. The various mounting bars also tend to flex and bend during a spraying operation, especially when the guns are being vertically moved by the oscillator. In some spray systems, the gun bodies can be quite long, thereby compounding any vibration and flexing of the gun mount arrangement.
Powder spray guns, especially electrostatic spray guns, tend to collect powder overspray on their exterior gun surfaces. This powder must be removed if the powder color is to be changed. A complete color change procedure can be slowed down by having a large number of surfaces inside the spray booth and on the gun bodies to be cleaned. Known powder spraying systems include air nozzles positioned near a spray gun to blow powder off the gun body. This can be accomplished, for example, as the guns are retracted from the booth by the gun mover. However, known systems are limited in that the air nozzles are fixed in position or otherwise not easily adjusted, and cannot be repeatedly-positioned at a predetermined location relative to the gun position. Gun positions may be changed, for example, depending on the object being sprayed.
With reference to FIGS. 1 and 2, a typical prior art powder spraying system 10 is illustrated with a prior art gun bar mounting configuration. The illustrations of FIGS. 1–2 are simplified in order to explain a typical application to which the present invention may be applied. The system 10 gun mount components illustrated in FIGS. 1–2 are well known.
The spray system 10 typically includes a spray booth 12 that partially encloses an object A being sprayed. The spray booth 12 may include a powder-collection system 14 to recover powder overspray. A powder feed hopper 16 holds a supply of spray powder that is fed to one or more spray guns 18 via powder feed lines 20. The spray guns 18 spray the object A non-electrostatically or with an electrostatically charged powder spray 22.
Known systems 10 often incorporate the use of a gun mover 30. The gun mover 30 includes a base 32 that supports a movable platform 34. A gun support 36 is vertically mounted on the movable platform 34. In the prior art, the gun support 36 is a fixed gun support that includes a number of horizontal support arms 37 that are mounted to a fixed stand 40. A number of vertical mounting bars 39 are attached to, the horizontal support arms 37. Horizontal gun mount bars 38 to which the spray guns 18 are removably attached as by any conventional clamp assembly, for example, may also be used. The spray guns 18 may also be mounted directly to the vertical bars 39. The fixed stand 40 is generally vertically oriented and securely mounted on the movable platform 34. By “fixed” is simply meant that the guns 18 are moved only by the mover 30, in a single direction parallel with the translation axis of the platform 34 as denoted by the directional arrow B in FIG. 1. The stand 40 may also be a gun oscillator, as is known in the art. Such an oscillator imparts vertical position control and movement to the guns attached to the oscillator, thus allowing vertical and horizontal position control of the guns 18.
The gun mover 30 further includes a control system 42 for programmable control of the position of the guns 18. The control system 42 includes a control device 44. The control device 44 may be used to control position of the guns in the spray booth, operation of the oscillator, and operation of the spray guns.
The present invention is directed to a repeatable and stable spray gun mounting arrangement, an adjustable and repeatable gun blow off arrangement, and a powder spraying apparatus that can utilize the gun mounting and blow off arrangements to facilitate quicker color change operations.